Re: doc elisp intro cross reference fixes

[Luc Teirlinck]

Richard Stallman wrote:

   Giving users a way to avoid repeated :group specifications could be
   convenient, but it looks like this way of doing it is unreliable.
   So let's consider another way: a special expression

     (defcustom-group FOO)

   which would mean, "use group FOO by default for the rest of this file, or
   until another defcustom-group."  This way, just changing the defgroups
   would not alter the default for :group in any defcustom.

That would also have the advantage that the defgroup would not need to
be in the same file.  For instance, except for one poor little orphan
that got kicked into the `nil' group, all defcustoms in ada-xref.el
belong to the group ada, but that group is defined in ada-mode.el.

Sincerely,

Luc.